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Diffstat (limited to 'Documentation/networking/devlink')
| -rw-r--r-- | Documentation/networking/devlink/stmmac.rst | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/Documentation/networking/devlink/stmmac.rst b/Documentation/networking/devlink/stmmac.rst index e8e33d1c7baf..47e3ff10bc08 100644 --- a/Documentation/networking/devlink/stmmac.rst +++ b/Documentation/networking/devlink/stmmac.rst @@ -19,13 +19,22 @@ The ``stmmac`` driver implements the following driver-specific parameters. - Type - Mode - Description - * - ``ts_coarse`` + * - ``phc_coarse_adj`` - Boolean - runtime - - Enable the Coarse timestamping mode. In Coarse mode, the ptp clock is - expected to be updated through an external PPS input, but the subsecond - increment used for timestamping is set to 1/ptp_clock_rate. In Fine mode - (i.e. Coarse mode == false), the ptp clock frequency is adjusted more - frequently, but the subsecond increment is set to 2/ptp_clock_rate. + - Enable the Coarse timestamping mode, as defined in the DWMAC TRM. + A detailed explanation of this timestamping mode can be found in the + Socfpga Functionnal Description [1]. + + In Coarse mode, the ptp clock is expected to be fed by a high-precision + clock that is externally adjusted, and the subsecond increment used for + timestamping is set to 1/ptp_clock_rate. + + In Fine mode (i.e. Coarse mode == false), the ptp clock frequency is + continuously adjusted, but the subsecond increment is set to + 2/ptp_clock_rate. + Coarse mode is suitable for PTP Grand Master operation. If unsure, leave the parameter to False. + + [1] https://www.intel.com/content/www/us/en/docs/programmable/683126/21-2/functional-description-of-the-emac.html |